The present invention relates to a sample inspection apparatus for analyzing a semiconductor sample or the like, and a method for producing an absorbed electron current image using the sample inspection apparatus. Particularly, it relates to a technique for specifying an electrically faulty point in wiring of a semiconductor sample or the like.
With development of finer devices, it has been difficult to specify a faulty point in a semiconductor sample having a circuit formed in the semiconductor surface, and it has taken enormous time to analyze the fault. For this reason, analyzers such as OBIRCH (Optical Beam Induced Resistance Change) or EB testers are used currently.
In the field of fault analysis in semiconductor samples, attention has been recently paid to wiring fault analyzing techniques in which the surface of a semiconductor sample is irradiated with an electron beam and a current absorbed from the wiring or a secondary signal emitted from the semiconductor sample is analyzed/imaged.
For example, a technique to bring probes into contact with the opposite ends or one side of a wiring pattern formed in a semiconductor sample, scan the wiring pattern on the semiconductor sample with an electron beam, and measure/image a current flowing through the probes to thereby specify a faulty point has been disclosed in JP-A-2002-368049.
A technique to amplify signals from a plurality of probes, obtain a differential signal between the signals, and scan the differential amplified signal to thereby display an image, and a technique to make a scan with a modulated electron beam for irradiation, and scan a signal similar to the aforementioned differential amplified signal to thereby display an image has been disclosed in JP-A-2003-86913.